“These guidelines were updated on January 1st, 2011.
All EarthCaches published prior to this date should be reviewed by the cache owner and if necessary, edited to comply with current guidelines.
EarthCaches not meeting current guidelines are not grandfathered.”
Source: http://support.groundspeak.com/index.php?pg=kb.page&id=292

7. Requests for photographs must be optional.
Exceptions to this guideline will only be considered if the requested photograph is related to an Earth Science logging activity such as recording a phenomenon.
This particular guidelines was updated on 1 January 2011.
All EarthCaches must conform to this guideline as photo requests are considered “optional tasks” and follow the guidelines set forth by Geocaching.com.
Existing EarthCaches that do not meet this guideline must be updated to comply.
Cache owners may not delete the cacher’s log based solely on optional tasks.
Source: http://www.geosociety.org/earthcache/guidelines.htm